1. Field of the Invention
This invention relates to a drill scope for a hand held drill that assists the user in drilling at a desired angle of inclination or tilt. More specifically, this invention relates to an adjustable spirit level with protractor setting for maintaining the angle of inclination during drilling.
2. Description of the Prior Art
The basic concept of controlling the relative or absolute angle of tilt or inclination during drilling with a conventional drill is a well established commercial practice. Thus, virtually every machinist and machine shop is capable of drilling at a prescribed angle using various fixtures and a drill press or the like. However, the concept of using a hand drill at a predetermined arbitrary angle still represents a serious limitation to the use of such tools.
Various attempts have historically been proposed with varying degrees of success to control the angle of drilling by using a bubble spirit level attached to the drill. Thus, it is known to attach a spirit level to a hand held drill to insure that the drill is being held level. Also, it has been proposed to employ two levels to maintain either horizontal or vertical positioning of the drill during drilling. It has also been suggested to calibrate the glass face of the spirit level to achieve a range of angles. However, such an approach sacrifices accuracy in that the sensitivity of the bubble float diminishes drastically. Thus, an inexpensive and convenient method of maintaining the angle of a hand held drill during drilling to within a few degrees is still needed.